For next prerelease we got a nice example to show how to get an image with retina awareness in the toolbar:

We put two images together in one NSImage. The green one is retina (2x) and the blue one is the normal one (1x). Depending on the screen, the icon will switch automatically. The example uses different colors to show the change. Of course you should use the same icon in different resolutions.
23 10 15 - 19:40

two comments

using the default Xojo toolbar already uses sharp images. You only have to make sure you are using images thats are 2x bigger.Pete (Email) - 25 10 15 - 09:41

Oh. Well, didn’t check that before. Anyway, the key here is to provide two images which can be different in detail.Christian Schmitz (URL) - 25 10 15 - 09:47